Remote control system for a locomotive with solid state tilt sensor

ABSTRACT

A portable master controller for a locomotive remote control system. The portable master controller has a user interface for receiving commands to control the movement of the locomotive. The user interface is responsive to operator commands to generate control signals. A processing unit receives the control signals from the user interface to generate digital command signals directing the movement of the locomotive. A transmission unit receives the digital command signals and generates a RF transmission conveying the digital command signals to the slave controller. A solid-state tilt sensor in communication with the processing unit communicates inclination information to the processing unit about the portable master controller. The processing unit receives and processes the inclination information. If the inclination information indicates that the portable master controller is in an unsafe operational condition, the processing unit generates an emergency digital command signal to the transmission unit, without input from the operator, for directing the locomotive to acquire a secure condition.

FIELD OF THE INVENTION

[0001] The present invention relates to an electronic system andcomponents thereof for remotely controlling a locomotive. The system hasa tilt sensor designed to operate in low temperatures often encounteredin northern regions.

BACKGROUND OF THE INVENTION

[0002] Economic constraints have led railway companies to developportable master controllers allowing a ground-based operator to remotelycontrol a locomotive in a switching yard. The portable master controllerhas a transmitter communicating with a slave controller on thelocomotive by way of a radio link. To enhance safety, the portablemaster controller carried by the operator is provided with atilt-sensing device to monitor the spatial orientation of the portablemaster controller and determine occurrence of operator incapacitatingevents, such as the operator tripping and falling over objects and lossof conscience due to a medical condition, among others. When thetilt-sensing device reports that the portable master controller isoutside the normal range of inclination, the portable master controllerwill automatically generate, without operator input, a command signalover the radio link to stop the locomotive.

[0003] Tilt-sensing devices used by prior art portable mastercontrollers are in the form of mercury switches. Those have provenunreliable in cold temperature operations where the mercury bead in theswitch can freeze and loose mobility. Attempts to overcome this drawbackinclude adding thallium to the mercury to lower its freezing point. Thissolution, however, is objectionable because thallium is a toxicsubstance. Hence, for environmental reasons, thallium is very rarelyused in the industrial community.

[0004] Against this background, the reader will appreciate that a clearneed exists in the industry to develop a system and components thereoffor remotely controlling a locomotive, featuring tilt-sensing devicesthat can reliably operate in very low temperatures and do not usemercury or thallium materials in their construction.

SUMMARY OF THE INVENTION

[0005] In one broad aspect, the invention provides a portable mastercontroller for a locomotive remote control system. The portable mastercontroller has a user interface for receiving commands to control amovement of the locomotive. The user interface is responsive to operatorcommands to generate control signals. The portable master controllerincludes a processing unit receiving the control signals from the userinterface to generate digital command signals directing the movement ofthe locomotive. A transmission unit receives the digital command signalsand generates a RF transmission conveying the digital command signals tothe slave controller.

[0006] A solid-state tilt sensor in communication with the processingunit communicates inclination information to the processing unit aboutthe portable master controller. The processing unit receives andprocesses the inclination information. If the inclination informationindicates that the portable master controller is in an unsafeoperational condition, the processing unit generates an emergencydigital command signal to the transmission unit, without input from theoperator, for directing the locomotive to acquire a secure condition.

[0007] By “solid-state” is meant a tilt sensor that does not uses aliquid to produce inclination information.

[0008] In a specific and non-limiting example of implementation, thesolid-state tilt sensor includes a single axis accelerometer responsiveto the acceleration of gravity. Optionally, the accelerometer is amulti-axis device responding to vertical acceleration and accelerationin at least another axis, as well. The ability to assess accelerationlevels in axes other than the vertical axis permits detection of unsafeconditions that do not necessarily translate into. an excessiveinclination of the portable master controller.

[0009] The inclination information sent by the solid-state tilt sensorcan be in any form as long as it allows the processing unit to detect anunsafe operational condition. The determination as to what is safe andwhat is unsafe can vary greatly according to the specific application.All the variants, however, include a common denominator, which is anassessment of the degree of inclination of the portable mastercontroller. In addition to the assessment of the degree of inclination,other parameters may be taken into account, such as the time duringwhich the portable master controller remains beyond a certaininclination angle, among others.

[0010] Once the occurrence of an unsafe operational condition has beendetected, the processing unit generates an emergency command signal todirect the locomotive to acquire a secure condition. A “secure”condition is a condition in which the risk of accident from thelocomotive is substantially reduced. An example of a secure condition isstopping the locomotive.

[0011] In a second broad aspect, the invention provides a remote controlsystem for a locomotive including in combination the portable mastercontroller defined broadly above and the slave controller for mountingon-board the locomotive.

[0012] In third broad aspect, the invention provides a portable mastercontroller that uses an accelerometer to generate inclinationinformation.

[0013] Under a fourth broad aspect, the invention provides a remotecontrol system for a locomotive that has a portable master controllerusing an accelerometer to generate inclination information.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] A detailed description of examples of implementation of thepresent invention is provided hereinbelow with reference to thefollowing drawings, in which:

[0015]FIG. 1 is a functional block diagram of the remote control systemfor a locomotive according to a specific and non-limiting example ofimplementation of the invention;

[0016]FIG. 2 is a structural block diagram of the portable mastercontroller of the system shown in FIG. 1;

[0017]FIG. 3 is a structural block diagram of the slave controller ofthe system shown in FIG. 1; and

[0018]FIG. 4 is a flow chart illustrating a diagnostic procedure toidentify a malfunction of the solid state tilt sensor.

[0019] In the drawings, embodiments of the invention are illustrated byway of example. It is to be expressly understood that the descriptionand drawings are only for purposes of illustration and as an aid tounderstanding, and are not intended to be a definition of the limits ofthe invention.

DETAILED DESCRIPTION

[0020]FIG. 1 is a high-level block diagram of a remote control system 10for a locomotive. The remote control system 10 includes a portablemaster controller 12 that is carried by a human operator. The system 10also includes a slave controller 14 mounted on-board the locomotive(locomotive not shown in the drawings). The portable master controller12 and the slave controller 14 exchange information over a radio link16.

[0021] The portable master controller 12 includes a user-interface 18through which the operator enters commands to control the movement ofthe locomotive. Such commands may include forward movement, backwardmovement, movement at a certain speed, coasting, stopping, etc.Optionally, the user interface 18 also conveys information to theoperator, such as status information, alarms, etc. The user-interface 18may comprise a variety of input mechanisms to permit the user to entercommands. Those input mechanisms may include electromechanical knobs andswitches, keyboard, pointing device, touch sensitive surface and speechrecognition capability, among others. Similarly, the user-interface 18may comprise a variety of output mechanisms to communicate informationto the user such as visual display or audio feedback, among others.

[0022] The user-interface 18 generates control signals 20, whichrepresent the inputs of the operator. In instances where theuser-interface 18 also communicates information to the operator, datasignals 22 are supplied to the user-interface 18 from a processing unit24, to be described below. The data signals convey the information thatis to be communicated to the user.

[0023] The processing unit 24 receives and processes the control signals20. The extent of the processing performed by the unit 24 will depend onthe particular control strategy implemented by the system 10. At itsoutput, the processing unit 24 will issue digital command signals 26that direct the operation of the locomotive. Those command signals 26represent commands, such as move forward, move backwards, stop, move ata selected speed, throttle command, brake command, among others.

[0024] The command signals 26 are supplied to a transmission unit 28that generates a Radio Frequency (REF) transmission conveying thosecommands over the RF link 16 to the slave controller 14.

[0025] The slave controller 14 is comprised of a receiver module 30 forsensing the RF transmission over the RF link 16. The receiver module 30generates at its output digital command signals 32 that are passed to aprocessing module 34 that processes those signals and issues localsignals 36 that control the locomotive. The local signals 36 include,for example, throttle settings, brake settings, etc.

[0026] An important feature of the system 10 is a tilt sensor 38 that ispart of the portable master controller 12. The tilt sensor 38 producesinclination information about the portable master controller 12 andsends this inclination information to the processing unit 24. Theprocessing unit 24 will analyze this information to determine if theportable master controller 12 is in a potentially unsafe operationalcondition. In the affirmative, the processing unit 24 generatesinternally an emergency digital command signal directing the locomotiveto acquire a secure condition. The digital command signal is sent to theslave controller via the transmission unit 28 and the radio link 16.

[0027] The inclination information processing strategy, which determinesif the portable master controller 12 is in an operational condition thatis safe or unsafe, can greatly vary and can take into account variousparameters. One of those parameters is the degree of inclination of theportable master controller 12. In one example, the degree of inclinationcan be quantified in terms of angle of inclination. Another parameter isthe time during which the portable master controller 12 is maintained ator beyond a certain degree of inclination. One possible strategy is todeclare an unsafe operational condition only after a certain degree ofinclination has been maintained for a predetermined time period, thusavoiding issuing the emergency digital command signal in cases where theoperator moves his body in such a way that it will excessively tilt theportable master controller 12, but only for a moment.

[0028] The reader will appreciate that a wide variety of inclinationinformation processing strategies are possible without departing fromthe spirit of the invention. All those strategies rely on the degree ofinclination as parameter, alone or in combination with other parameters.

[0029] In a specific example of implementation, the tilt sensor 38 is anaccelerometer that is responsive to static gravitational acceleration.By “static” it is meant that the accelerometer senses the force ofgravity even when the portable master controller 12 is not movingvertically up or down. The accelerometer is mounted in the casing of theportable master controller 12 such that the axis along which theacceleration is sensed coincides with the vertical axis. When theportable master controller 12 is inclined, the component of the force ofgravity along the vertical axis changes which allows determining thedegree of inclination of the portable master controller 12.

[0030] Optionally, the accelerometer may also be sensitive about axesother than the vertical axis to detect abnormal accelerations indicativeof potentially unsafe conditions that may not translate in an abnormalinclination of the portable master controller 12. Examples of such otherabnormal accelerations arise when the portable master controller 12 (orthe operator) is severely bumped without, however, the operator fallingon the ground.

[0031] In a possible variant the tilt sensor 38 may include a pluralityof accelerometers, each accelerometer being sensitive in a differentaxis.

[0032] When the tilt sensor 38 includes an accelerometer that outputs asignal having both a dynamic and a static component, it is desirable tofilter out the dynamic component such as to be able to more easilydetermine or derive the orientation of the master controller 12.Techniques to filter out the dynamic component of the output signal areknown in the art and will not be discussed here in detail.

[0033] If the processing unit 24 recognizes an unsafe operationalcondition, it issues an emergency command signal to secure thelocomotive. One example of securing the locomotive includes directingthe locomotive to perform to stop.

[0034] In a specific and non-limiting example of implementation the tiltsensor 38 is based on an accelerometer available from Analog DevicesInc. in the USA, under part number ADXL202. The output of the tiltsensor 38 is a pulse width modulated signal, where the width of thepulse indicates the degree of inclination.

[0035] For safety reasons, it is desirable for the processing unit 24 todetermine when the tilt sensor 38 may be malfunctioning. At this end theprocessing unit 24 has diagnostic unit 25 that implements a diagnosticprocedure. The diagnostic procedure runs continuously during theoperation of the master controller 12. The flow chart of the diagnosticprocedure is shown at FIG. 4. The procedure starts at step 100. At step102 the signal from the tilt sensor 38 is received by the processingunit 24. The diagnostic procedure then performs two series of actionsdesigned to confirm the proper operation of the tilt sensor 38 and thecontinued operation of the tilt sensor 38. The proper operationprocedure will be described first. At step 104 a timer is started. Thetimer runs for a predetermined period of time. For example, this periodof time can be from a couple of seconds to a couple of minutes. Decisionstep 26 detects changes in the output signal of the tilt sensor 38. If achange is noted, i.e., indicating a movement of the master controller12, the timer 104 is reset. If no change is noted i.e., indicating alack of master controller movement during the predetermined time period(the timer expires), the step 108 is initiated.

[0036] The step 108 verifies the integrity of tilt sensor 108 byperforming a calibration test. This is effected by subjecting the tiltsensor 38 to a known condition that will produce a variation in theoutput signal. One possibility is to subject the tilt sensor 38 to aself-test which will induce a change in the output signal. Sending acontrol signal to a pin of the tilt sensor 38 initiates such self-test.At step 110, the processing unit 24 observes the output signal and if achange is noted, which indicates that no detectable malfunction ispresent, then processing continues at step 100. Otherwise, theconditional step 110 branches to step 112 that triggers an alarm. Thealarm may be an audible, visual (or both) indication on the userinterface 18 that a malfunction has been noted. Once the alarm at step112 has been triggered, one possibility for the processing unit 24 is togenerate an emergency digital command signal to the transmission unit 28without input from the operator, for directing the locomotive to acquirea secure condition.

[0037] The continued operation procedure is performed at the same timeas the proper operation procedure. The continued operation procedureincludes a decision step 114 at which the output signal of the tiltsensor 38 is validated. In this example, the validation includesobserving the signal to determine if it is within a normal range ofoperation. For example, when the output signal of the tilt sensor 38 isa pulse width modulated signal (PWM) the decision step 114 screens thesignal continuously and if the frequency of the signal falls outside thenormal range of operation of the tilt sensor 38 or the signal disappearsaltogether, a tilt sensor failure is declared. When such tilt sensorfailure occurs, the alarm 112 is triggered and the locomotive brought toa secure condition, as described earlier.

[0038] It should be noted that the diagnostic procedure implemented bythe processing unit 24 might vary from the example described earlierwithout departing from the spirit of the invention. For instance, thediagnostic procedure may include only the steps necessary to perform theproper operation procedure without the steps for performing thecontinued operation procedure. Alternatively, the diagnostic proceduremay include only the steps necessary to perform the continued operationprocedure without the steps for performing the proper operationprocedure. Objectively, both the proper operation and continuedoperation procedures are desirable from the standpoint of enhancedsafety, however one of them can be omitted while still providing atleast some degree of protection against tilt sensor failure.

[0039]FIG. 2 is a structural block diagram of the portable mastercontroller 12. The portable master controller 12 is largely softwareimplemented and includes a Central Processing Unit (CPU) 40 thatconnects with a data storage medium 42 over a data bus 44. The datastorage medium 42 holds the program element that is executed by the CPU40 to implement various functional elements of the portable mastercontroller 12, in particular the processing unit 24. Data is exchangedbetween the CPU 40 and the data storage medium 42 over the data bus 44.Peripherals connect to the data bus 44 such as to send and receiveinformation from the CPU 40 and the data storage medium 42. Thoseperipherals include the user interface 18, the transmission unit 28 andthe tilt sensor 38.

[0040] It should be noted that the diagnostic unit 25 (shown in FIG. 1)is implemented in software by the processing unit 24. Alternatively, thediagnostic procedure may be implemented partly in hardware and partly insoftware or only in hardware.

[0041]FIG. 3 is a structural block diagram of the slave controller 14.As is the case with the portable master controller 12, the slavecontroller 14 has a CPU 46 connected to a data storage medium 48 with adata bus 50. The data storage medium 48 holds the program element thatis executed by the CPU 46 to implement various functional elements ofthe slave controller 14, in particular the processing module 34.Peripherals connect to the data bus 50 such as to send and receiveinformation from the CPU 46 and the data storage medium 48. Thoseperipherals include the receiver module 30 and an interface 52 throughwhich the slave controller 14 connects to the locomotive controls.

[0042] Although various embodiments have been illustrated, this was forthe purpose of describing, but not limiting, the invention. Variousmodifications will become apparent to those skilled in the art and arewithin the scope of this invention, which is defined more particularlyby the attached claims.

1.) A portable master controller for a locomotive remote control system,the locomotive remote control system having a slave controller mountedon-board a locomotive, said portable master controller comprising: a) auser interface for receiving commands to control a movement of thelocomotive from a human operator, said user interface being responsiveto the commands from the human operator to generate control signals; b)a processing unit in communication with said user interface forreceiving the control signals to generate digital command signals fordirecting the movement of the locomotive; c) a transmission unit incommunication with said processing unit for receiving the digitalcommand signals and for generating an RF transmission conveying thedigital command signals to the slave controller; d) a solid-state tiltsensor in communication with said processing unit for supplying to saidprocessing unit inclination information about said portable mastercontroller, said processing unit: i) being operative to determine atleast in part on the basis of the inclination information if saidportable master controller is in a safe operational condition or in anunsafe operational condition; ii) when said processing unit determinesthat the portable master controller is in an unsafe operationalcondition said processing unit is operative to generate an emergencydigital command signal to said transmission unit without input from theoperator, for directing the locomotive to acquire a secure condition. 2)A portable master controller as defined in claim 1, wherein saidsolid-state tilt sensor includes an accelerometer. 3) A portable mastercontroller as defined in claim 2, wherein said accelerometer responds tostatic gravitational acceleration. 4) A portable master controller asdefined in claim 3, wherein said accelerometer generates an outputsignal including a static component representative of the staticgravitational acceleration and a dynamic component representative ofdynamic-acceleration. 5) A portable master controller as defined inclaim 4, wherein said processing unit is operative to filter out thedynamic component. 6) A portable master controller as defined in claim3, wherein the emergency digital command signal directs the locomotiveto stop. 7) A portable master controller as defined in claim 3, whereinsaid processing unit includes a diagnostic unit to detect a malfunctionof said tilt sensor. 8) A portable master controller as defined in claim7, wherein said diagnostic unit is operative to perform a properoperation procedure. 9) A portable master controller as defined in claim8, wherein said proper operation procedure implements a timer to measurea time during which said tilt sensor supplies inclination information tosaid processing unit indicating that an orientation of said mastercontroller does not change. 10) A portable master controller as definedin claim 9, wherein said timer defines a maximal time period, when theinclination information supplied by said tilt sensor to said processingunit indicates that the orientation of said master controller has notchanged during said maximal time period, said diagnostic unit isoperative to send a signal to said tilt sensor to force said tilt sensorto supply inclination information indicating a change of orientation ofsaid master controller. 11) A portable master controller as defined inclaim 7, wherein when said diagnostic unit detects a malfunction of saidtilt sensor, said processing unit is operative to generate an emergencydigital command signal to said transmission unit without input from theoperator, for directing the locomotive to acquire a secure condition.12) A portable master controller as defined in claim 8 wherein saiddiagnostic unit is operative to perform a continued operation procedure.13) A portable master controller as defined in claim 12, wherein saidtilt sensor generates an output signal indicative of the inclinationinformation, said continued operation procedure including validating theoutput signal of the tilt sensor. 14) A portable master controller asdefined in claim 13, wherein the validation of the output signalincludes observing a characteristic parameter of the output signal. 15)A portable master controller as defined in claim 14, wherein thecharacteristic parameter of the output signal is a frequency of theoutput signal. 16) A portable master controller as defined in claim 4,wherein said signal output by said tilt sensor is a pulse widthmodulated signal. 17) A remote control system for a locomotive,comprising: a) a portable master controller, including: i) a userinterface for receiving commands to control movements of the locomotivefrom a human operator, said user interface being responsive to thecommands from the human operator to generate control signals; ii) aprocessing unit in communication with said user interface for receivingthe control signals to generate digital command signals for directingthe movement of the locomotive; iii) a transmission unit incommunication with said processing unit for receiving the digitalcommand signals and for generating a RF transmission conveying thedigital command signals to the slave controller; b) a solid-state tiltsensor in communication with said processing unit for supplying to saidprocessing unit inclination information about said portable mastercontroller, said processing unit: i) being operative to determine atleast in part on the basis of the inclination information if saidportable master controller is in a safe operational condition or in anunsafe operational condition; ii) when said processing unit determinesthat the portable master controller is in an unsafe operationalcondition said processing unit is operative to generate an emergencydigital command signal to said transmission unit without input from theoperator, for directing the locomotive to acquire a secure condition; c)a slave controller for mounting on-board the locomotive, said slavecontroller including: i) a receiver module for sensing the RFtransmission; ii) a processing module in communication with saidreceiver module, said processing module being responsive to digitalcommand signals conveyed by the RF transmission to generate localsignals controlling the locomotive. 18) A remote control system asdefined in claim 17, wherein said solid-state tilt sensor includes anaccelerometer. 19) A remote control system as defined in claim 18,wherein said accelerometer responds to static gravitationalacceleration. 20) A remote control system as defined in claim 19,wherein said accelerometer generates an output signal including a staticcomponent representative of the static gravitational acceleration and adynamic component representative of dynamic acceleration. 21) A remotecontrol system as defined in claim 20, wherein said processing unit isoperative to filter out the dynamic component. 22) A remote controlsystem as defined in claim 19, wherein the emergency digital commandsignal directs the locomotive to stop. 23) A remote control system asdefined in claim 19, wherein said processing unit includes a diagnosticunit to detect a malfunction of said tilt sensor. 24) A remote controlsystem as defined in claim 23, wherein said diagnostic unit is operativeto perform a proper operation procedure. 25) A remote control system asdefined in claim 24, wherein said proper operation procedure implementsa timer to measure a time during which said tilt sensor suppliesinclination information to said processing unit indicating that anorientation of said master controller does not change. 26) A remotecontrol system as defined in claim 25, wherein said timer defines amaximal time period, when the inclination information supplied by saidtilt sensor to said processing unit indicates that the orientation ofsaid master controller has not changed during said maximal time period,said diagnostic unit is operative to send a signal to said tilt sensorto force said tilt sensor to supply inclination information indicating achange of orientation of said master controller. 27) A remote controlsystem as defined in claim 23, wherein when said diagnostic unit detectsa malfunction of said tilt sensor, said processing unit is operative togenerate an emergency digital command signal to said transmission unitwithout input from the operator, for directing the locomotive to acquirea secure condition. 28) A remote control system as defined in claim 24wherein said diagnostic unit is operative to perform a continuedoperation procedure. 29) A remote control system as defined in claim 28,wherein said tilt sensor generates an output signal indicative of theinclination information, said continued operation procedure includingvalidating the output signal of the tilt sensor. 30) A remote controlsystem as defined in claim 29, wherein the validation of the outputsignal includes observing a characteristic parameter of the outputsignal. 31) A remote control system as defined in claim 30, wherein thecharacteristic parameter of the output signal is a frequency of theoutput signal. 32) A remote control system as defined in claim 20,wherein said signal output by said tilt sensor is a pulse widthmodulated signal. 33) A portable master controller for a locomotiveremote control system, the locomotive remote control system having aslave controller mounted on-board a locomotive, said portable mastercontroller comprising: a) a user interface for receiving commands tocontrol a movement of the locomotive from a human operator, said userinterface being responsive to the commands from the human operator togenerate control signals; b) a processing unit in communication withsaid user interface for receiving the control signals to generatedigital command signals for directing the movement of the locomotive; c)a transmission unit in communication with said processing unit forreceiving the digital command signals and for generating an RFtransmission conveying the digital command signals to the slavecontroller; d) an accelerometer in communication with said processingunit for supplying to said processing unit inclination information aboutsaid portable master controller, said processing unit: i) beingoperative to determine at least in part on the basis of the inclinationinformation if said portable master controller is in a safe operationalcondition or in an unsafe operational condition; ii) when saidprocessing unit determines that the portable master controller is in anunsafe operational condition said processing unit is operative togenerate an emergency digital command signal to said transmission unitwithout input from the operator, for directing the locomotive to acquirea secure condition. 34) A remote control system for a locomotive,comprising: a) a portable master controller, including: i) a userinterface for receiving commands to control movements of the locomotivefrom a human operator, said user interface being responsive to thecommands from the human operator to generate control signals; ii) aprocessing unit in communication with said user interface for receivingthe control signals to generate digital command signals for directingthe movement of the locomotive; iii) a transmission unit incommunication with said processing unit for receiving the digitalcommand signals and for generating a RF transmission conveying thedigital command signals to the slave controller; b) an accelerometer incommunication with said processing unit for supplying to said processingunit inclination information about said portable master controller, saidprocessing unit: i) being operative to determine at least in part on thebasis of the inclination information if said portable master controlleris in a safe operational condition or in an unsafe operationalcondition; ii) when said processing unit determines that the portablemaster controller is in an unsafe operational condition said processingunit is operative to generate an emergency digital command signal tosaid transmission unit without input from the operator, for directingthe locomotive to acquire a secure condition; c) a slave controller formounting on-board the locomotive, said slave controller including: i) areceiver module for sensing the RF transmission; ii) a processing modulein communication with said receiver module, said processing module beingresponsive to digital command signals conveyed by the RF transmission togenerate local signals controlling the locomotive.